Sept. 26, 2025
Mayo Clinic has the multidisciplinary expertise to safeguard both fetal and maternal health during in utero repair of myelomeningocele. The surgery helps prevent the progression of neural damage that occurs during gestation after the initial failure of primary neurulation.
"The effects on the brain are reversed in the overwhelming majority of fetuses who have this operation," says Edward S. Ahn, M.D., a pediatric neurosurgeon at Mayo Clinic in Rochester, Minnesota. "We have about 10 years of experience with caring for these families, so we are equipped to manage any potential consequences to the mother and the fetus."
Myelomeningocele is associated with pronounced central nervous system conditions, including posterior fossa hypoplasia, hindbrain herniation and hydrocephalus. Individuals commonly have paralysis, cognitive deficits, and bladder or bowel dysfunction.
In addition to including pediatric neurosurgeons, Mayo Clinic's in utero myelomeningocele repair team comprises maternal-fetal medicine specialists, maternal and fetal anesthesiologists, neonatologists, and pediatric cardiologists.
"Patients benefit from an incredibly skilled, multidisciplinary team, all under one roof," says Mauro H. Schenone, M.D., a specialist in Maternal and Fetal Medicine at Mayo Clinic's campus in Minnesota. "Our goal is to get the patient back home while our team partners with referring physicians to provide the care needed. If the referring center has the resources needed for delivery and neonatal care, we work with the referring team to make this happen. Otherwise, the patient always has the option of delivering at Mayo Clinic."
Steps to ensure safety
Myelomeningocele is generally diagnosed through routine fetal ultrasound during the second trimester of pregnancy. The spinal defect can disrupt cerebrospinal fluid (CSF) flow, causing a Chiari 2 malformation and hydrocephalus. Babies born with myelomeningocele and hydrocephalus typically need surgery to correct the spinal defect, followed by additional surgeries to implant ventriculoperitoneal shunts. Treating the myelomeningocele in utero reduces the risk of needing a shunt.
"The effects on the brain are reversed in the overwhelming majority of fetuses who have this operation."
Prenatal surgery risks triggering preterm labor. However, more than half of patients who have prenatal myelomeningocele repair at Mayo Clinic deliver their babies at 36 to 37 weeks of gestation. The average gestational age of babies born after the prenatal procedure at Mayo Clinic is 34.2 weeks.
To maximize safety, Mayo Clinic's care team carefully reviews the records of patients referred for myelomeningocele repair. "The criteria for prenatal surgery include the presence of hindbrain herniation, spinal lesion between T1 and S2, and the absence of unassociated fetal anatomic or genetic abnormalities that compromise the potential benefit of in utero repair," Dr. Schenone says.
The benefits of prenatal repair also include a higher probability of independent walking. "In a developing fetus, an exposed spinal cord may experience damage over time. Covering the defect surgically might protect the spinal cord and benefit motor capacity," Dr. Ahn says.
Hydrocephalus also is less severe. "Babies who have prenatal surgery need fewer shunts," Dr. Ahn says. "That's a long-term implication because a functioning ventriculoperitoneal shunt is often a lifelong requirement. That means a person is constantly dependent on medical assessments to avoid or manage malfunctions in the future."
At Mayo Clinic, patients deemed candidates for prenatal repair have ultrasound and MRI scans as well as detailed clinical evaluations. The fetal multidisciplinary team meets to discuss the results. "Unless we all agree that the benefits of prenatal treatment outweigh the risks, we don't proceed," Dr. Schenone says.
Surgery is performed between 23 and 25 weeks of gestation. "That is early enough to mitigate the potential consequences of neural tissue being exposed in utero while balancing the risk of triggering preterm labor or rupture of membranes," Dr. Schenone says. The entire care team attends detailed surgical planning sessions.
While fetoscopic repair has been performed at Mayo Clinic, an open surgical approach is preferred. "We feel that the integrity of the closure is greater than what currently can be achieved with a fetoscope. And a good closure is paramount to preventing CSF leaks," Dr. Ahn says. Open surgical repair requires subsequent Cesarean delivery. Mayo Clinic physician-scientists are investigating alternative minimally invasive approaches, potentially involving robotics.
"Patients benefit from an incredibly skilled, multidisciplinary team, all under one roof."
Pediatric cardiologists monitor the fetus's heart throughout the surgery. Medication can be given or the fetus's position changed if needed to maintain cardiac stability. "These steps are key to preventing preterm delivery," Dr. Schenone says. "At Mayo Clinic, our pediatric team is stationed in the neonatal room, which is next to the fetal operating room and equipped with all the resources needed to care for the neonate if an emergency delivery occurs."
Patients are usually hospitalized for several days after the prenatal repair. Once discharged, patients are asked to remain close to Mayo Clinic for a week. "They can then go home and stay in contact through video conferencing or in-person consultations," Dr. Schenone says. "We're used to treating patients from afar. We've learned through decades of experience who are the patients who need to stay and those who can go home."
When prenatal myelomeningocele repair was introduced over a decade ago, the criteria for surgery were strict. They included restrictions on the patient's body mass index (BMI) and glycemic control as well as the presence of fetal anomalies unassociated with myelomeningocele.
"With experience, we've become more flexible," Dr. Schenone says. "Our approach now is individualized and focused on the benefit-to-risk ratio. We have expanded our inclusion criteria to BMI under 40 and have successfully performed the procedure in patients with complex situations, such as type 1 diabetes. Mayo Clinic endocrinologists can work with mothers to control diabetes in the weeks between myelomeningocele diagnosis and prenatal repair and still provide the option of in utero surgery."
Mayo Clinic specialists can also help manage any postnatal effects of myelomeningocele, including hydrocephalus. "We're learning more about when children need a shunt," Dr. Ahn says. "We've found that many children can be treated instead with endoscopic third ventriculostomy. Our rate of not having to insert a shunt is very high."
As a multidisciplinary center, Mayo Clinic offers lifelong support. The Spina Bifida Clinic coordinates care for children and teenagers with complex conditions of the spine, spinal cord, brain, bowel and bladder. Those patients can later transition to a Mayo Clinic healthcare team for adults with spina bifida.
"The benefit we offer is the great collaboration among specialties," Dr. Ahn says. "We're able to manage all the potential consequences of this prenatal surgery and to really care for families."
For more information
Refer a patient to Mayo Clinic.